Lithological features of surface sediment and their influence on organic m atter distribution across the East-Siberian Arctic shelf

The Arctic is undergoing rapid climate change, which affects the global and regional carbon cycles. The East Siberian Arctic shelf, that is believed to store huge amounts of organic carbon in different pools, has been the subject of growing scientific interest in recent decades. The aim of the work was to study the lithological features of bottom sediments on the East Siberian Arctic shelf and to assess their influence on the spatial distribution of organic material in the study area. Materials and methods. The sediment samples were collected during the 45-day multidisciplinary SWERUS-C3 expedition on IB ODEN in summer 2014. Surface sediments from inner and middle East Siberian Arctic shelf were collected in summer 2008 during the International Siberian Shelf Study (ISSS-08) campaign onboard the HV Yakob Smirnitsky. The samples were analyzed for the grain size and specific surface area characteristics and total organic carbon content. It is shown that the subglacial sedimentation and the accumulation of predominantly fine-grained sediments prevail within the study area. Nevertheless, atypical sand zones were identified on the outer shelf. The authors have suggested several external factors, including modern and paleo ice scouring in the early Holocene, and intensive gas venting, which are accompanied by removal of fine-grained sediments. The paper considers spatial distribution of organic matter in the bottom sediments of the East Siberian Arctic shelf and its interrelation with their lithological properties.